Mobile communication systems were developed to provide mobile users with communication services. With the rapid advance of technologies, the mobile communication systems have evolved to the level capable of providing high speed data communication service beyond the early voice-oriented services.
Recently, standardization for a Long Term Evolution (LTE) system, as one of the next-generation mobile communication systems, is underway in the 3rd Generation Partnership Project (3GPP). LTE is a technology designed to provide high speed packet-based communication of up to 100 Mbps and aims at commercial deployment around 2010 timeframe. In order to accomplish the aim, a discussion is being held on several schemes: one scheme for reducing the number of nodes located in a communication path by simplifying a configuration of the network, and another scheme for maximally approximating wireless protocols to wireless channels.
Meanwhile, unlike voice service, the data service is provided on the resource determined according to the data amount to be transmitted and channel condition. Accordingly, the wireless communication system, especially cellular communication, is provided with a scheduler manages transmission resource allocation in consideration of the required resource amount, channel condition, data amount, etc. This is the fact in the LTE system as the next generation mobile communication system, and the scheduler located at an evolved Node B (eNB) manages the transmission resource allocation.
Recent studies are focused on the LTE-Advanced (LTE-A) for improving data rate with the adoption of various new technologies to the LTE communication system. Among them, some technologies are taken into consideration for Heterogeneous Network (HetNet) environment and Distributed Antenna System (DAS). The HetNet denotes a wireless network made up of a plurality of cells having various sizes and capabilities such as macro cells, pico cells, and femto cells. In such a way of distributing small cell eNBs different in size from the macro eNB or transmit/receive antenna within the macro cell area, it is possible to provide the UE with the best service. Particularly from the view point of UE power consumption, the power consumption of the UE can be improved by receiving signals from a plurality of eNBs or using a plurality of reception antennas.